.box{
    width: 80%;
    height: 750px;
    background-color: rgb(135, 206, 235);
    margin:  auto;
}
.mtk{
    width: 450px;
    height: 350px;
    position: absolute;
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    margin: auto;
    padding: 50px;
    background-color: white;
    box-sizing: border-box;
    display: none;
    z-index: 1;
}
.zzc{
    left: 0;
    right: 0;
    top: 0;
    bottom: 0;
    position: fixed;
    z-index: 0;
    display: none;
    background-color: rgb(0, 0, 0,0.3);
}
tbody.ghbs tr:nth-child(odd){
    background-color: pink;
}
tbody.ghbs tr:nth-child(even){
    background-color: yellow;
}
tbody.yrbs tr:hover{
    background-color: green;
}